I recently bought an 89 190e2.6 with 105k miles for one of my kids to drive. The car is in mint condition, but salls unpredictably and stumbles at the same time on restart. It will then drive perfectly for a day or so. I have checked all electrical grounds(ok), the fuel pump relay, and have run Injector cleaner thru a tank of gas.
I would appreciate a few hints as to which way to proceed from here.(I am replacing the fuel filter this weekend).
Thanks
jdk

------------------
jdk

How did you check the fuel pump relay? Also the overvoltage relay can cause this as can the ignition coil.


------------------
Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Benzmac,
I am the actual driver of the car. Thank's for the info in response to my dad's posting. We are checking out your suggestions right away.
I have a better description of the problem that might help with any diagnosis.
The car will be running fine, then randomly the check engine light may flicker. There is an abrupt power loss(car slows down by 5 to 10mph) (then return) as the light goes off then back on. This may happen then no problem for a day or so. At other times the light will stay on and i have to pull over because i can not keep up with traffic. I turn the car off for a minute the restart and most of the time the problem dissapears. The stalling comes sometimes when i come to a stop while the light is flickering. The revs tend to jump slightly then bottom out as the car dies. If i put the car in neutral and keep the revs up I can keep the car from stalling.
Hopefully the added description may help narrow down the problem.
Thanks for your time

TRK

Replace the O2 sensor and away you go. It sounds as if the sensor is shorting to ground or something...If this doesn't take care of it, have it looked over by a pro!

------------------
Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Great! Thanks for the help. we are currently also deoxing all electrical contacts and making sure all are secure. Doing that cured my old 300se of a few quirks and stumbles.
Next is replacement of mbtex on door panels. Some of it is splitting.

------------------
jdk

jdk, what are you using to de-ox your electrical connectors? I used a wire brush on the terminal block of my SD, but wonder if there is something more effective/less work. As I troubleshoot various parts of this car's electricals, I'd like to clean all the contacts that I pull apart.

------------------
Robert W. Roe
1983 300SD 264K mi

There is a product called Contact OL made by the Wurth co. You may be able to find it at some MB specialty shops.

------------------
Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Robert,I use a dremel tool to burnish the contacts and then I spray Caig DeOx , a product used in electronics to treat the terminals.This is safe for all electrical and electronic use.
To Benzmac, the O2 sensor is new and is good. We checked the relays by substituting good ones from another car. Im afraid we will have to go to the dealer to check the computer. We will keep you updated


------------------
jdk